Bursting head device

ABSTRACT

Provided are articulating, rotating pipe bursting head devices for bursting a buried pipe and simultaneously pulling a replacement pipe through the same location. The bursting heads can comprise an integrated, substantially hollow cone body having one or more cutting knives arranged radially about its outer surface, and an end cap at its posterior end. Protruding from the posterior end of the end cap is a swiveling quick release coupling means for linking the bursting head to a replacement pipe carrier such as a universal duct puller. The swiveling quick release coupling means allows for rotation and articulation of the replacement pipe relative to the bursting head during operation, enhancing entry of the replacement pipe into an existing pipe underground. The bursting head body further can comprise an axial opening at its anterior end for receiving a cable, an internal magnetized cable gripping mechanism and a quick-release tool.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Provisional Application No.61/768,543, filed Feb. 25, 2013, the disclosure of which is herebyexpressly incorporated in its entirety by reference herein.

FIELD OF USE

Embodiments of the present disclosure find applicability in the field ofsystems designed to pull cable and/or pipe through space underground.One useful field includes systems for bursting and replacing gas, water,sewer or other underground pipes.

BACKGROUND

This disclosure relates to devices and methods typically used forsimultaneously bursting or destroying buried pipes and pulling areplacement pipe though the same location as the destroyed pipe. Suchmethods of pipe replacement are sometimes referred to as “trenchlesspipe replacement systems” and require only two pits to be dug, one ateach end of the pipe to be replaced. One end of a pulling cable isattached to the front end of a bursting pipe head device, and the otherend is threaded through the existing pipe from an entry point accessiblein the entry pit and provided to a pulling apparatus located in the exitpit. The pulling apparatus then pulls the cable and the attachedbursting pipe head device through the existing cable, typically by ahydraulic mechanism. The bursting pipe head device bursts or fracturesthe existing pipe as it is pulled through, and brings with itreplacement or product pipe attached at the back end of the burstingpipe head device.

There is an on-going desire to minimize the size of the pits to be dug;increase the facility and ease for (1) introducing replacement pipe intothe existing pipe location, (2) pulling the replacement pipe through theexisting pipe; and (3) disengaging the cable and removing the burstingpipe head device from the replacement pipe once it is in place; as wellas increasing the facility and ease of maintaining and using a burstingpipe head device.

Bursting head devices and methods of use are well-known andcharacterized in the art. Typically, these devices include (1) a pipebursting head typically having a tapered nose or leading portion andstructured to break apart the existing pipe as the bursting head ispulled through the existing buried pipe, (2) a cable connection thatallows cable to pull the pipe breaking head through the existing buriedpipe, and (3) a means for connecting new replacement pipe to the backend of the bursting head so that the cable pulls the new pipe into andthrough the existing buried pipe as it is burst by the bursting head.Typically, a hydraulic pulling device pulls the cable and the attachedbursting head and replacement pipe through existing buried burst pipe.

The bursting pipe head devices of the art typically have a static,non-flexible means for connecting the new pipe to the back end of thebursting head device. This inability to allow movement, rotation orflexing at the connection point makes entry of the new pipe into theexisting pipe at the starting point or entry pit difficult, oftenrequiring the need to dig a larger pit than desired, so as to reduce theangle of entry of the new pipe into the buried pipe.

In addition, existing bursting pipe head devices of the art typicallyuse a pin and clevis type arrangement external to and extending from thefront end of the device to attach cable to the bursting head, typicallyby means of a swaged connection. Alternatively, the cable is attached tothe bursting head by means of an internal clamping mechanism. Theexternal cable attachment devices are limited in utility in thatexternal attachment adds to the overall length of the device, therebylimiting the distance the bursting head device can be pulled into theexit or pulling pit from the buried pipe terminus with pulling devicesof the art. This can require the need to dig the bursting head deviceout of the earth. The internal clamping mechanisms of the art also canbe difficult and problematic from which to disengage the cable easilyonce the replacement pipe is in place. Moreover, where the cableconnection is by means of an internal clamping mechanism, ready accessto the internal clamping mechanism and/or ease of cable release islacking in the pipe bursting head devices of the art.

US Patent Application Publications 2002/0081154 A1, US 2008/0181728, andUS 2012/0321391 A1, and U.S. Pat. No. 6,357,967 B1 and U.S. Pat. No.6,913,091 B2 are representative of the state of pipe bursting headdevices and methods of use in the art.

The present disclosure describes improvements in the bursting headdevice and method of use that overcomes deficiencies in the burstingpipe head devices and methods of the prior art.

SUMMARY OF THE INVENTION

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This summary is not intended to identify key features ofthe claimed subject matter, nor is it intended to be used on its own asan aid in determining the scope of the claimed subject matter.

In accordance with one embodiment of the present disclosure, anarticulating, rotating pipe bursting head device is provided. Moreparticularly, the improved pipe bursting head device disclosed hereincomprises a coupling means at the back or posterior end of the burstingpipe head device which connects the bursting pipe head device to thereplacement or product pipe, typically through a universal duct pullerattached to the front or anterior end of the product pipe. In onepreferred embodiment, the coupling means allows for articulation of thereplacement pipe relative to the bursting pipe head device. In anotherpreferred embodiment, the articulating coupling means allows forarticulation from 0° through 90°. In another embodiment, the couplingmeans allows for rotation of the replacement pipe relative to the pipebursting head device. In another embodiment this rotating coupling meansallows for 360° rotation. Thus, the present disclosure describes anarticulating, rotating bursting pipe head device and method of use.

In accordance with another embodiment of the present disclosure, thecoupling mechanism disclosed herein allows for quick attachment andrelease of a product or replacement pipe from a pipe bursting headdevice or cone without requiring bolting. In one embodiment, thecoupling mechanism comprises a clevis fastener means comprising a clevisprotruding from the back or posterior end of the bursting pipe headdevice, a tang protruding from the front or anterior end of theuniversal duct puller, and a clevis pin that engages the clevis and thetang. In another embodiment the clevis pin is threaded and thecorresponding openings on the clevis and tang are dimensioned to receivethe clevis pin also are threaded to receive and hold the clevis pin,thereby securely coupling the universal duct puller to the bursting pipehead device without need for a cumbersome bolting mechanism. Release ofthe clevis pin allows quick release of the universal duct puller andattached product pipe from the bursting pipe head device. In a preferredembodiment the back or posterior end of the bursting pipe head devicecomprises a detachable end cap with an axial opening and the cleviscomprises an independent, internally located component that protrudesthrough the end cap axial opening and acts as a swivel. The clevisswivel component comprises a posterior end and an anterior end. Theposterior end of the clevis swivel component comprises the clevis and isdimensioned to pass through and protrude from the end cap axial opening,and the anterior end is dimensioned to be larger than the end cap axialopening such that the clevis component sits against the interior surfaceof the end cap and can swivel relative to and independent of the end capwhen seated against the end cap. In another embodiment, the anterior endof the clevis component acts as a bracer or backstop for a compressiblespring and free cable end in the clamping mechanism disclosed herein.Similarly, the tang also can protrude through an axial opening at theanterior end of the universal duct puller, such that it too acts as anindependently swiveling component relative to the pipe pullingmechanism.

In accordance with another embodiment of the present disclosure, amagnetized internal cable clamping mechanism is used to attach thepulling cable to the bursting pipe head device. The improved internalcable clamping or cable gripping mechanism disclosed herein comprises aplurality of 2 to 4 pieces which together form a cone whose outercamming surface engages the interior surface of the bursting head cone,and whose inner surface is threaded and defines an axial hole of adimension to engage the cable surface and bite into the cable.Accordingly, the cable clamping or gripping members act like cableclamping jaws, also known in the art as cable gripping jaws or cablegripper jaws. In addition, the joining surface on each member piece ofthe cable clamping cone comprises a magnet located to align with themagnet on the corresponding joining surface of the other member piece orpieces, and indexed so that all the magnets either are positive ornegative and will repel one another when the member pieces are joinedand the magnets are aligned. In one embodiment, the magnetized internalcable clamping mechanism comprises three member pieces. In anotherembodiment, the magnet is embedded in the member joining surface suchthat it lies flush with the member joining surface. In still anotherembodiment, the magnet is located at the balance point of the cableclamping member. When used in the method described herein, the improvedmagnetized cable clamping mechanism acts as a part of a quick cablerelease mechanism, improving the facility and ease of disengaging apulling cable from a bursting pipe head device.

In accordance with another embodiment of the present disclosure, abursting pipe head device is provided comprising a housing with twomembers: a pipe bursting head cone and a mechanically detachable end capthat fits into the back or posterior end of the cone. In a preferredembodiment the end cap engages with the head cone by means of an easilyremovable quick-locking mechanism, allowing easy access to the interiorof the head cone. In still another preferred embodiment thequick-locking mechanism comprises a twist-locking mechanism. In anotherembodiment the interior surface of the head cone has a smaller diameterthan the exterior surface and its posterior axial opening is dimensionedto receive the end cap. Further, the posterior axial opening comprisestwo slots spaced 180° apart and, 90° to each slot, comprises aprotrusion. Similarly, the engaging anterior end of the end cap has asmaller diameter than its posterior end, and comprises two protrusionsspaced 180° apart and dimensioned to fit in and pass through the slotson the interior surface at the posterior end of the head cone. Theengaging anterior end of the end cap also comprises two slots spaced180° apart and 90° to each protrusion on the end cap, dimensioned toallow the protrusions on the posterior end of the head cone to fit inand pass through the slots on the end cap. When the protrusions on theend cap are fit into and pass through their corresponding slots on thehead cone, the end cap and cone are engaged. The end cap then can berotated or twisted 90° or 270° such that the protrusions on the end capnow lie anterior to the protrusions on the head cone and the end cap isin a locked position. In another preferred embodiment, the lockedposition of the end cap is indexed and fastened by means of a set screwwhich passes through a threaded opening dimensioned to receive the setscrew in the end cap and a corresponding recess on the head coneposterior surface, typically at 90° to one of the head cone slots. Instill another embodiment, the quick-locking end cap disclosed hereinfurther comprises an axial opening or hole smaller than the diameter ofthe head cone engaging mechanism and dimensioned to receive the cleviscomponent disclosed herein.

In accordance with another embodiment of the present disclosure, a cableengaging and quick-release mechanism, tool and method are provided. Inone preferred embodiment, a bursting pipe head device comprising aninternal cable engaging mechanism and quick-release tool is disclosed.In another preferred embodiment, a bursting pipe head cone is providedwhose anterior end defines a threaded axial hole or opening. Alsoprovided is a mechanical screw comprising threads and dimensioned to fitand screw into the threaded axial hole or opening of the bursting coneanterior. The mechanical screw itself defines an axial hole dimensionedto receive and allow a free cable end to pass through, and its anteriorsurface comprises two slots spaced 180° apart. Each slot of themechanical screw is competent to receive the spanner pin of a cablerelease spanner tool or key disclosed herein. In one preferredembodiment the mechanical screw comprises left-handed threads.

In another embodiment, a cable release spanner tool or key is disclosed,wherein the tool body comprises (half) of a cylindrical body having anaxial opening of a dimension such that the cylindrical body of the toolcan engage or lay or sit on a cable. The anterior end of the spannertool comprises two spanner pins spaced 180° apart, each dimensioned tofit in the spanner slots of the mechanical screw. The spanner toolfurther comprises means for turning the tool once the spanner pins ofthe tool are engaged in the spanner slots of the mechanical screw. Inanother embodiment, the spanner tool comprises a means for facilitatingturning the screw. In a preferred embodiment, the tool comprises atleast one and preferably two arms that extend radially from the tool'scylindrical body, each arm spaced 180° apart and providing the means forturning the mechanical screw. In another embodiment the inner surface ofthe spanner tool cylindrical body comprises a magnet such that thespanner tool is engaged with the cable on which it sits by means ofmagnetic attractive force. In still another embodiment, the magnet isembedded in the internal surface of the tool's cylindrical body suchthat it lies flush with the internal surface of the cylindrical body. Inanother embodiment the cable engaging and quick-release mechanismdisclosed herein comprises (1) the cable quick release tool disclosedherein; (2) the threaded mechanical screw; (3) the magnetized cableclamping mechanism disclosed herein; (4) a compressible spring thatengages the posterior surface of the magnetized clamping mechanism; and(5) a surface posterior to the spring that is competent to brace theback end of the spring and restrict lateral movement of the spring andmagnetized clamping mechanism. In another embodiment the brace, alsoreferred to herein as a backstop, comprises the anterior end of theclevis component disclosed herein. In still another embodiment, thespring defines an axial opening competent to receive a free cable endand allow it to pass therethrough.

The cable engaging and quick release method disclosed herein comprisesproviding a bursting pipe head device having a substantially hollowcylindrical body comprising a cone having an axially hollow interior, athreaded opening at its anterior end, and an end cap at its posteriorend. The end cap and cone together, when engaged, define an interiorcavity competent to house, in anterior progression from the end capinterior, the following components: a spring bracing surface, acompressible spring, the magnetized cable clamping mechanism disclosedherein, and the threaded mechanical screw disclosed herein. Each ofthese components, together with the end cap and cone, are dimensionedaxially such that, when the mechanical screw is at least partiallythreaded into the anterior opening of the cone, the posterior end of thescrew is contiguous with the anterior end of the magnetized cableclamping mechanism, the posterior end of which is contiguous with theanterior end of the compressible spring, and the posterior end of thecompressible spring is contiguous with the bracing surface or backstop.In a preferred embodiment the bracing surface comprises the anterior endof the clevis swivel component disclosed herein. The free end of a cableis then provided to the interior of the bursting head cone by feedingthe cable through the axial hole of the mechanical screw. The quickrelease spanner tool or key then is placed on the cable so that thespanner pins on the tool engage with the spanner slots on the mechanicalscrew, and the tool is rotated about the cable to thread the mechanicalscrew into the cone's anterior opening. This process pushes the cableclamping members apart and compresses the spring behind them. The cableend then is manually pushed further into the cone head such that itpasses beyond the cable clamping mechanism. In one preferred embodiment,the cable passes through the spring and comes to rest against thebracing surface. The spanner tool then is turned in the oppositedirection to unscrew the mechanical screw until its anterior surface isflush with the cone head's anterior opening. As the screw is moved backout of the cone head interior, the spring decompresses and the cableclamping members are pushed forward towards the cone nose until itsinterior dimensions limit further forward movement of the cable clampingcone, forcing the cable clamping cone members down onto the cablesurface. The interior threaded surfaces of the clamping members allowthe members to bite into the cable, acting like a clamping jaw. Thecable now is engaged in the bursting pipe head device and ready forpulling. As force is applied pulling the cable, for example into andthrough the underground pipe to be replaced, the cable clamping membersact as chinese handcuffs, increasing their grip on the cable by means ofthe serrations, teeth or threaded ridges on their cable engagingsurfaces as the limiting tapered bursting head nose interior surfacefurther compresses the members together and down on to the cablesurface.

Once replacement or product pipe is in place, and/or an operator desiresto release the cable from the bursting head device, the spanner tool isplaced back on the cable, the tool's spanner pins are engaged in thespanner slots on the mechanical screw, and the spanner tool turned tothread the screw back into the cone interior, which compresses thespring and releases the clamping jaw members from the cable surface,allowing the cable to be pulled out of the cone head opening. In apreferred embodiment the mechanical screw comprises left-hand threadsand the spanner tool is turned clock-wise to thread the screw into thecone head interior and expand the cable clamping mechanism to allowentry or exit of a free cable end, and turned counter-clockwise tounthread the screw out of the cone head interior sufficient to expandthe spring and push the clamping mechanism down onto a cable surface. Inanother preferred embodiment the cable clamping jaw members aremagnetized such that adjoining members repel each other sufficiently topush the members back and away from the cable surface and each other intheir disengaged open position such that they do not interfere with thecable as it is being extracted.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisdisclosure will become more readily appreciated as the same becomebetter understood by reference to the following detailed descriptionwhen taken in conjunction with the accompanying drawings, wherelike-numbered parts reference like-membered components and wherein:

FIG. 1 is an exploded view of a bursting pipe head device in accordancewith embodiments of this disclosure, coupled to a universal duct pullerin accordance with one embodiment of this disclosure;

FIG. 2 is an exploded view of a bursting pipe head device in accordancewith embodiments of this disclosure comprising a quick-locking nose conehead and end cap in accordance with one embodiment of this disclosure;

FIGS. 3A and 3B illustrate (A) the interlocking surface of the end capillustrated in FIG. 2 in accordance with one embodiment of thisdisclosure; and (B) the end cap interlocking surface of the burstingcone illustrated in FIG. 2 in accordance with one embodiment of thisdisclosure;

FIG. 4 is a cross-section view of a bursting pipe head device inaccordance with embodiments of this disclosure, coupled to a universalduct puller in accordance with one embodiment of this disclosure;

FIGS. 5A and 5B illustrate (A) the coupling mechanism in accordance withone embodiment of this disclosure and useful for coupling a pipebursting head device to a product pipe; and (B) examples of theavailable articulation and rotation possible with this couplingmechanism;

FIG. 6 is an exploded view of a cable clamping mechanism in accordancewith an embodiment of this disclosure; and

FIG. 7A-7D illustrate (A) the mechanical screw illustrated in FIG. 1;(B) the threaded axial opening at the anterior end of the nose cone,ready to receive the mechanical screw; (C) a quick release cable spannertool in accordance with one embodiment of this disclosure; and (D) thespanner tool sitting on the cable about to engage with the threadedmechanical screw spanner slot.

DETAILED DESCRIPTION

Embodiments of the present disclosure provide devices, components,mechanisms and methods of use directed to trenchless systems for pullinga cable or replacement pipe through an existing underground pipe.

Referring to FIGS. 1 & 2, one embodiment of an improved bursting pipehead device in accordance with the present disclosure is shown. Thebursting head device 10 comprises a conically shaped bursting cone 20and an end cap 100 at its posterior end. As will be understood by thoseof ordinary skill in the art, the anterior portion of the conicalbursting cone has an outer diameter that is less than the interiordiameter of an existing pipe to be fractured or cut, and a posterior endthat is larger than the interior diameter of the existing pipe, so that,as the bursting pipe head device is being pulled through the existingpipe, it fractures or cuts or bursts the pipe by virtue of its size. Thedevice of the present disclosure is useful for bursting pipe of myriadmaterials including, without limitation, tile, cement and PVC. Ifdesired, the bursting cone can include one or more sharpened cuttingknives 30 arranged radially about the cone head. The knives can bemechanically attached or welded on or machined integrally with the conehead body. The embodiment shown in FIG. 1 illustrates a blade 30 thatsits in a channel 31 on the cone head outer surface, the knife beingattached to the cone head body by means of a pin 50. Component 40 is a“blank” dimensioned to sit in channel 31 such that it lies flush withthe cone body outer surface, in the event a blade on the cone bodysurface is not desired or needed. The blank 40 also is attached to thecone body surface by means of a pin 50. Useful blade lengths range fromabout 1-inch to 5-inches, and have an angle in the range of about15°-35°, more preferably in the range of about 20-25°. The blade orblades serve to concentrate stress on the inside of brittle pipe,particularly cement or tile pipe, causing them to fracture. Where theexisting pipe is plastic the blades typically are competent to cutthrough the pipe. Of course, as will be appreciated by those havingordinary skill in the art, the bursting cone can be constructed withouta channel 31 or a blade 30.

Useful cone body lengths and angles can vary and it is within the skillin the art to manipulate these for a desired outcome. Typically, thesmaller the bursting pipe head device, the further the device can bepulled into the exit pit, which can make for easier cable extraction andproduct pipe release. Useful cone body lengths for bursting 4-inch pipefor example, range from about 6 inches to 12 inches, typically in therange of about 8 inches to 10 inches. Useful cone body outer angles onthe devices of the present disclosure range from about 15° to 40°, moretypically in the range of about 20° to 30°. Similarly, useful interiorcone body angles typically are about half those of the selected outerangle. These ranges are well known to those of ordinary skill in theart.

The cone head body 20 is hollow or at least partially or substantiallyso, and has an opening 21 at its anterior end into which a compressingelement 60 can be threaded. In one embodiment the compressing element isa mechanical screw. In another embodiment the mechanical screw threadsinto the anterior opening 21 of the cone head body using left-handedscrew threads. The compressing element also defines an axial hole oropening competent to receive the free end of a cable. As will bedescribed in detail below, the compressing element is part of thecable-engaging and quick-release mechanism of the present disclosure. Aswill be understood by those of ordinary skill in the art, as the engagedcable (see below) is pulled, it tends to try to unwind in a clock-wiseor right-handed manner. This natural tendency of the cable puts forcepressure on the mechanical screw threaded into the cone head body andwould tend to unscrew it if it were threaded with right-handed threads.

Referring now to FIGS. 1-4, a bursting pipe head device 10 is showncomprising a cone 20 and a quick-locking end cap 100. Theinterconnecting surfaces of the end cap 100 and the cone body 20 aredimensioned to match one another, providing a flush surface at theconnection point 126, FIGS. 2 and 4. The quick-locking mechanismdescribed herein allows easy and ready access to the interior of thehead cone body and the components inside. In one embodiment shown inFIG. 3B, the posterior end of the cone head body 123 has an innersurface 125 that defines a narrower diameter than the outer surface 124,the inner surface being dimensioned to receive the end cap. In anotherembodiment the inner surface 125 defines two slots 113 spaced 180° apartand, 90° to each slot a protrusion defining a lip 114, for a total oftwo protrusions or lips spaced 180° apart.

Similarly, the engaging anterior end of the end cap 121 (FIG. 3A)comprises an inner surface 118 that defines a neck having a narrowerdiameter than the outer surface 222 at the posterior end of the end cap117. In one embodiment, the inner surface 118 defines a diameterequivalent to and matches the inner surface diameter 125 of the conehead posterior end. The anterior end of the end cap further comprisestwo protrusions 110 spaced 180° apart and dimensioned to fit in and passthrough the two slots 113 on the cone head. It will be appreciated bythose of ordinary skill in the art that, if desired, the slots andprotrusions on either the end cap or cone body could be located at anangular distance different than 90° from each other, and that what iskey is that the angular distance selected is the same on both the endcap and the cone body. It also will be appreciated that, while two slotsand two protrusions are shown in the illustrative embodiment provided inFIG. 3, a fewer or larger number of slots and protrusions can befabricated. Again, what is key is that the number of slots andprotrusions selected correspond on both the end cap and the cone body.

The engaging anterior end of the end cap also comprises two slots 111spaced 180° apart and 90° to each protrusion 110, the slots 111 beingdimensioned to allow the protrusions 114 on the head cone to fit in andpass through them. When the end cap protrusions 110 are fit into andpass through the slots 113 on the cone head, the end cap and cone bodyare engaged. The end cap then can be rotated or twisted 90° or 270° suchthat the end cap protrusions 110 now lie anterior to the protrusions 114of the cone body and the end cap is now in a locked position. In anotherembodiment the locked position of the end cap is fastened by means of aset screw 120 that passes through a threaded opening 119 dimensioned toreceive the set screw and located on the end cap outer diameter surface.In still another embodiment, a recess 115 located at the 90° and/or 270°position on the cone body outer surface identifies the position fortightening the set screw with, for example, an allen wrench 116 (FIG.4), allowing the locked position to be easily located and indexed.

Referring now to FIGS. 1-5, one embodiment of an improved means forcoupling the bursting pipe head device to a product pipe carrier 160 isshown. Typically, the product or replacement pipe carrier comprises auniversal duct puller 160. However, other product pipe carriercomponents or means for engaging and carrying a product pipe 170 arecontemplated to be useful and are not considered central to the presentdisclosure. The coupling means disclosed herein allows for quickattachment and release of the product pipe carrier component withoutrequiring bolting or other attachment means of the prior art.

In one embodiment the coupling mechanism comprises a clevis 131protruding from an axial opening in the end cap 100 posterior end 117(FIG. 3A), a tang 130 protruding from the anterior end of the productpipe carrier means 160, and a clevis pin 140. It will be appreciated bythose having ordinary skill in the art that the tang can be integral tothe pipe pulling mechanism, or it can protrude through an opening in theanterior end of the mechanism as embodied in FIG. 1. In one preferredembodiment the clevis pin 140 is threaded 134 (FIG. 5A) as are thecorresponding clevis pin holes or openings in the clevis arms 132 andthe tang 133 dimensioned to receive the clevis pin, such that when theclevis pin is threaded into the clevis pin holes on the clevis and tang,the bursting pipe head device is secured to the product pipe carriercomponent. Releasing the bursting pipe head device from the product pipecarrier component requires only unthreading or otherwise removing theclevis pin from the tang and clevis. In addition, the clevis, tang andpin arrangement together allow for the product pipe carrier to bearticulated up to 90° in any direction relative to the bursting pipehead device (FIG. 5B). This has the advantage of allowing flexibilitybetween the product pipe carrier component and the bursting pipe headdevice. In the devices of the prior art the coupling mechanism rendersthe product pipe fixed and static relative to the bursting pipe headdevice, making entry of the replacement or product pipe into theexisting pipe opening in the entry pit difficult. The sharp angle ofentry that results from an inflexible coupling mechanism often requireddigging larger entry pits than desired, and/or providing strong bracing,and/or providing mechanical adaptions and wedging so as to minimize theangle of entry of the replacement pipe and bring the product pipe intoalignment with the pipe bursting head and the existing pipe entry point.With the articulating coupling mechanism disclosed herein, these entryissues are obviated or substantially reduced.

In another embodiment, the clevis 131 is associated with the end cap 100in such a way as to allow articulation and rotation (FIG. 5B) of theproduct pipe relative to the bursting pipe head device. Moreparticularly, in a preferred embodiment the end cap posterior end 117comprises an axial opening 122 dimensioned to receive and allow theclevis to pass through and protrude therefrom. (FIGS. 2 and 3A). Theanterior end 91 of the clevis component has a diameter 90 larger thanthe axial opening 122 such that the clevis component sits against theinterior surface of the end cap posterior axial opening and theprotruding clevis can swivel 360° in the opening. When the clevis andtang are engaged, the product pipe now can swivel in any directionrelative to the bursting pipe head (FIG. 5B), allowing the product pipeto be pulled into and through existing pipes having corners or angles,and/or changes in depth. As will be appreciated by those having ordinaryskill in the art, the independently rotating and swiveling clevis-tangcoupling mechanism allows full range of rotation and articulation of thereplacement pipe coupling mechanism 160 and pipe 170 about the burstinghead device (FIGS. 5A and 5B). In another preferred embodiment, the tang130 itself protrudes from an axial opening 223 in the anterior end ofthe replacement pipe pulling mechanism housing 161 (FIGS. 1 and 4),allowing the replacement pipe to rotate or swivel independently aboutthe tang barrel 224.

In another preferred embodiment the clevis swivel component 131 has ananterior end 91 dimensioned to receive a compressible spring 80. In oneembodiment the anterior end 91 comprises a flat, tapered, dimpled orconcave surface having a diameter competent to receive the posterior endof a spring 80. In another embodiment, the clevis swivel componentanterior end 91 defines an axial opening 92 having a diameter competentto receive the spring 80, the opening extending some distance into theclevis swivel component interior and terminating at some point withinthe clevis component so as to act as a brace or backstop 93 for theposterior end of spring 80 and against which the spring can be seated.In one embodiment, the axial opening extends in the range of about 0.25inches to 3 inches into the clevis swivel interior. In anotherembodiment, the axial opening extends 0.5 inches to 2 inches to theclevis swivel interior. In another embodiment, the brace or backstop isgenerated by reducing the diameter 90 of the axial opening, therebycreating a ledge 93 on which the spring sits. In another embodiment, theclevis axial opening terminates at a point distal to the backstop ledgethat seats the compressible spring, preferably tapering to a point, andhaving a diameter dimensioned to receive a free cable end. In anotherembodiment, the brace or backstop is created by eliminating the openingcompletely, creating a floor on which the spring sits. In still anotherembodiment the compressible spring 80 itself defines a hollow channeldimensioned to allow a free end of a cable 200 (FIG. 7D) to passtherethrough. In a preferred embodiment, the cable passes through thespring and continues further into the clevis component until itterminates at a tapered terminus of the clevis opening. In still anotherembodiment, the posterior end of the compressible spring 80 can beattached or joined or otherwise made integral with the backstop surfaceon the clevis anterior end axial opening such that the clevis andcompressible spring are one component. FIG. 3A illustrates one end capembodiment of the disclosure wherein the end cap posterior axial openinghas received the clevis 131 and the clevis anterior axial opening hasreceived the hollow compressible spring 80.

Referring now to FIGS. 1, 6 and 7, embodiments of a bursting pipe headdevice disclosed herein are shown, having an improved internal mechanismand means for engaging and releasing a pulling cable 200. Referring inparticular to FIGS. 6 and 7, a magnetized internal cable clamping orcable gripping mechanism 70 is shown. The mechanism comprises multiplemember pieces 77, typically between 2-4 pieces. In one embodimentillustrated herein, the clamping mechanism comprises three memberpieces. The member pieces fit together to define a hollow cone 70 havingan outer camming surface 78 competent to engage the interior surface ofthe bursting pipe head cone, and an inner surface 72 that defines anaxial hole or channel of a dimension and texture competent to engage apulling cable surface 200 and bite into the cable. In a preferredembodiment the outer camming surface 78 is smooth, reducing friction asthe camming surface moves along the interior surface of the burstinghead cone nose. The axial opening 72 provided by the member pieces isformed by a channel that runs centrally down the length of each memberpiece. In a preferred embodiment, the inner surface or channel 72 isthreaded such that the threads act like teeth to bite into the cable andthe cable clamping cone acts as a clamping jaw or cable gripping jaw.The joining surface 73 on each member piece comprises a magnet 74located to align with the magnet on the corresponding joining surface oneach member piece. In one embodiment, the magnet is embedded in themember joining surface such that it lies flush with the member joiningsurface. As will be appreciated by those having ordinary skill in theart, a range of magnet sizes and magnetic force may be used effectivelyin the devices disclosed herein. In one embodiment, a preferred magnetsize is ¼-inch by ¼-inch, although larger and smaller magnet sizes arecontemplated. In another embodiment, a magnet strength of N50 is used,and magnets of stronger and weaker strength also are contemplated. Aselected magnet strength will be competent to repel two adjacent memberjoining surfaces from one another. In another embodiment, the magnet islocated at the balance point on the member joining surface, and otherpositions on the member joining surface also can be used for locatingthe magnet, provided the position selected is the same on each memberjoining surface. In another embodiment, the magnets are indexed so thatthe same pole (positive or negative) is exposed on each member joiningsurface such that the magnets repel one another when two member joiningsurfaces are joined and the magnets are aligned. In the embodiment shownin FIGS. 6 and 7 the cable clamping cone 70 comprises three memberpieces 77 and one magnet per member joining surface 73. It will beappreciated by those skilled in the art that more magnets could beutilized if desired.

Referring now to FIGS. 1, 3B, 4 and 6, the cable clamping cone 70 has anangular ratio proportional to the angle of cone body hollow interior 79,such that the outer camming surfaces 78 of the cable clamping coneengage the interior surface of the bursting head cone, particularlytowards the anterior end of the head cone (FIG. 4). As illustrated inFIGS. 1 and 4, the cable clamping mechanism disclosed herein comprisesthe cable clamping cone 70 fitted into the cone head body 10, togetherwith a spring 80 the anterior end of which engages the posterior end ofthe clamping cone 70. The posterior end of the spring engages a bracingsurface 93 on the anterior end 91 of the clevis swivel component 131 orwithin the interior body of the component 131. In another embodiment,the compressible spring 80 may have a spanner element attached at itsanterior posterior end to extend the overall length of the springcomponent 80. In one embodiment, useful springs of the presentdisclosure are 1-inch to 5-inches in length. In another embodiment,useful springs are 1.5-inches to-3-inches in length. Preferred springlengths will depend on the overall length chosen for the bursting pipehead device, as well as the selected length of the cable clamping cone.As shown herein, the spring is manually seated in the clevis swivelcomponent. It also is contemplated that the posterior end of the springcould be welded or more permanently fixed to the clevis component ifdesired.

When the end cap 100 is locked into the cone body 10, the internalcomponents: clevis swivel, spring, and cable clamping cone are engagedwith one another at their anterior and posterior ends as described aboveand shown in FIGS. 1 and 4. As shown in FIGS. 1 and 3B, the anterior endof the cone body comprises an axial opening 21. The internal cableclamping mechanism of the present disclosure provides a means forintroducing into the axial opening 21 a member or element competent topass through the axial opening 21 and compress the cable clamping cone70 against spring 80 such that spring 80 is compressed against thebackstop or bracing surface, ledge or floor provided by clevis swivelcomponent 131, and the cable clamping cone members 77 are pushed backfrom the head cone nose 10 by the aligned, indexed and repelling magnets74 such that the member joining surfaces of each member 77 no longer arein contact. Moreover, the magnets 74 on the member surfaces 73 providerepelling forces such that the clamping cone members stay away from eachother in the absence of compression force from spring 80. As usedherein, this relative position of the cable clamping cone members isreferred to as their “dissociated position.”

The compressing element further has means for holding the spring in itscompressed position, and thereby holding the clamping cone members intheir dissociated position. The compressing element further has an axialopening of a diameter sufficient for a free cable end to passtherethrough and enter into the cone head interior. When the compressingelement is in its compressing, engaged position, the cable clamping conemembers are dissociated sufficiently that the cable can continue throughthe axial opening or channel 72 created by the member pieces, and on tothe backstop provided by the clevis swivel component. In one embodiment,the cable also passes through the axial opening of the compressedspring. In another embodiment, the cable backstop and the compressiblespring backstop are one and the same. In another embodiment, the cablebackstop occurs distal to the spring backstop.

Once the cable is in place against its backstop, the compressing elementis removed or extracted out from the cone body interior sufficiently toallow the compressible spring 80 to expand and push the cable clampingcone members forward into the cone head. The spring is of a length andforce sufficient to move the outer camming surfaces of the cableclamping members 77 against the interior walls of the nose body untilthe angle of the nose body interior limits further forward movement. Asthe forward movement of the clamping cone is inhibited, the cableclamping members are forced down onto the cable surface. Thus the spring80 provides sufficient compressible force to overcome the repellingforce of the magnets 74. The channel 72 of the cable clamping members,together defining the axial opening of the cable clamping cone, aretextured, preferably by means of being threaded, thereby providing meansto bite into the cable. The free end of the cable is now engaged in thebursting pipe head device. As the bursting pipe head device is pulledthrough the existing pipe by means of the cable that extends out fromthe front of the head cone body, the pulling motion tends to force thecable clamping members further forward into the cone nose theconstriction of which continually forces the members down onto the cablesurface such that they tend to increase their bite or grip on the cable.

When the bursting pipe head device and pulling apparatus have pulled theproduct pipe through the existing pipe, and the bursting pipe head hasarrived at the pulling or exit pit, the cable is released by re-engagingthe compressing element such that the cable clamping cone members 77 arepushed back down the nose cone body and away from the cable surface, andthe spring 80 is compressed against its backstop. The compressingelement once again is held in the compressing position, the repellingforce of the magnets again move the cable clamping members away fromeach other and the cable, and preferably actively pressed against theinterior surface of the bursting head cone body. The cable, nowdisengaged from the cable clamping cone members, can be pulled out ofthe nose body axial opening. Here again, the magnets 74 on the memberjoining surfaces 73 are aligned with one another and their repellingforce serves to keep the member pieces back and away from the cablesurface, allowing easy cable extraction without need of opening thebursting head device itself

An embodiment of the cable engaging and release mechanism of the presentdisclosure is shown in FIGS. 1 and 7. In this embodiment, thecompressing element comprises a threaded mechanical screw 60 (FIG. 7A)and the axial opening 21 of the nose body 20 is threaded and dimensionedto receive and engage the mechanical screw FIG. 7B. The threadedengagement holds the mechanical screw in its compressing position forintroducing a free cable end 200 into the nose cone body 20, and forextracting the free cable end from the nose cone body. Those of ordinaryskill in the art will appreciate that the length of the mechanical screwand the corresponding length of receiving threads in the cone head axialopening 21 will depend on the length of the cone head and thecorresponding length of the cable clamping cone 70 and compressiblespring 80. Useful mechanical screw lengths can range from 1-inch to7-inches, with typical lengths ranging in the vicinity of about of1.5-inch to 3-inches. In a preferred embodiment the mechanical screwdefines a left-threaded screw. Cables tend to unwind in a right-handedmanner as they are pulled, which would tend to unscrew the mechanicalscrew over time if its threads defined a right-threaded screw. Using aleft-threaded screw holds the screw in the axial opening as the cable ispulled and tends to unwind. The screw further comprises an axial openingor channel 62 dimensioned to allow a cable to pass therethrough (FIGS.7A and 7D). The threads on mechanical screw illustrated in theembodiments in FIGS. 4 and 7A do not extend the full length of thescrew, providing a hollow bore portion 63 for ease for seating themechanical screw in the cone body. In another embodiment, the threadscould extend the full length of the screw body.

In another embodiment of the present disclosure the compressing elementis engaged with the cable clamping mechanism by means of spanner key orspanner wrench 5 (FIG. 7C). The spanner key 5, also referred to hereinas a spanner tool or a cable release spanner tool, comprises two spannerpins 9 spaced 180° apart and dimensioned to fit into spanner pin slots61 spaced 180° apart on the anterior surface of the mechanical screw 62(FIG. 7A). In another embodiment the spanner key further comprises halfof a cylinder body 7 having an axial opening or channel dimensioned toallow the concave surface 7 of the cylinder to sit or lay on the cablesurface. In still another embodiment the inner concave surface of thecylinder body further comprises at least one magnet 8 and indexed suchthat the spanner key can engage the cable surface by means of attractivemagnetic force. In another embodiment the spanner key comprises a meansfor facilitating application of mechanical force to turn the mechanicalscrew with the spanner tool. In one embodiment, the means comprises anarm 6 extending from the spanner tool. In a preferred embodiment themeans comprises two arms 6 spaced 180° apart and extending laterallyfrom the cylinder body 7. The arms allow for easy turning of themechanical screw both (1) into the nose body such that the mechanicalscrew is in its engaged compressing position allowing a free cable endto be introduced or extracted from the nose body, and (2) out of thenose body sufficiently to allow the internal spring 80 to push the cableclamping cone members forward and onto the cable surface. In oneembodiment, the screw length and the axial opening threading length aredimensioned such that the screw is recessed into the threaded axialopening 21 when it is in the engaged, compressing position. In anotherembodiment, the mechanical screw head is substantially flush with theaxial opening 21 when it is in the non-compressing position, and a cableis engaged. FIG. 7D shows a mechanical screw 60 partially threaded intoa nose cone body 20, a spanner key 5 engaged with the screw head bymeans of the spanner pins 9 engaged with the spanner slots 61, the keyand screw being turned by means of the spanner arms 6. Sitting in thespanner key channel 7 is a cable 200. The mechanical screw is in anon-compressing position, and the free-end of a cable has beenintroduced into the nose body through the axial opening in themechanical screw.

Embodiments of the disclosure may be embodied in other specific formswithout departing from the spirit or essential characteristics thereof.The present embodiments are therefore to be considered in all respectsas illustrative and not restrictive, the scope of the disclosure beingindicated by the appended claims rather than by the foregoingdescription, and all changes that come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.While illustrative embodiments have been illustrated and described, itwill be appreciated that various changes can be made therein withoutdeparting from the spirit and scope of the disclosure.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A bursting head devicecomprising: (a) a cone head having a substantially hollow interior andan aperture at its anterior end dimensioned to receive a cable andthreaded to receive a hollow screw having an inner dimension competentto receive said cable; (b) an end cap having a substantially hollowinterior and coupling to the posterior end of said cone head by means ofa quick release interlocking mechanism at its anterior end, and (c) acable gripping mechanism housed in said cone head interior comprising:(i) a plurality of cable gripper jaws, the plurality of jaws togetherdefining a cone having an outer surface dimensioned to fit against theinterior of said bursting head at its anterior end and having a threadedinner surface competent to grip said cable, each said cable gripper jawmember comprising a magnet on each of its lateral interconnectingsurfaces, the magnet positioned to contact and repel the magnet on theproximal/neighboring jaw; and (ii) a compressible spring dimensioned tofit within said bursting head posterior to said cable gripper jaws suchthat, when said screw is threaded in said aperture, the plurality ofsaid cable gripping jaws are moved back in said bursting head,compressing said spring and releasing the jaws from the cable, themagnets repelling each other with sufficient force to keep the jawmembers off the cable and compressed against the interior surface of thebursting head.
 2. An articulating, rotating pipe bursting head devicefor bursting a buried pipe and pulling a replacement pipe through thesame location as the destroyed pipe, the bursting head devicecomprising: (a) a bursting head housing consisting essentially of (i) anintegrated, substantially hollow cone body, and (ii) an end cap coupledto the posterior end of said cone body, said cone body dimensioned toburst a pipe when pulled through said pipe; (b) a swiveling couplingmechanism protruding from the posterior end of said end cap, saidcoupling mechanism swiveling independent of said end cap and comprisingan arm having an opening for receiving a pin; (c) a replacement pipecarrier comprising a coupling mechanism protruding from the pipe carrieranterior end, said coupling mechanism comprising an arm having anopening for receiving a pin, and (d) a pin competent to pass througheach said opening thereby coupling said end cap to said replacement pipecarrier such that said replacement pipe carrier can rotate about saidbursting head housing and said replacement pipe carrier coupling arm canarticulate about said end cap coupling arm.
 3. The bursting head deviceof claim 2 wherein said cone body further comprises a cutting knife onits outer surface.
 4. The bursting head device of claim 2 wherein saidcoupling mechanism protruding from the anterior end of said replacementpipe carrier is competent to swivel independent of said replacement pipecarrier.
 5. The bursting head device of claim 2 wherein both saidcoupling mechanisms together define a clevis and tang fastener mechanismwhen coupled with said pin.
 6. The bursting head device of claim 2wherein said pin and said openings for receiving said pin are threaded.7. The bursting head device of claim 2 wherein said cone body furthercomprises an axial opening at its anterior end dimensioned to receive acable.
 8. The bursting head device of claim 7 wherein said cone bodyinterior houses a cable gripping mechanism comprising: a plurality ofinterconnecting cable gripper jaws, the plurality of jaws togetherdefining a cone having an outer surface dimensioned to fit against theinterior of said bursting head cone body at its anterior end and havinga threaded inner surface competent to grip a said cable, each said cablegripper jaw member comprising a magnet on each of its lateralinterconnecting surfaces, the magnet positioned to contact and repel themagnet on the adjacent jaw member.
 9. A pipe bursting head device forbursting a buried pipe and pulling a replacement pipe through the samelocation as the destroyed pipe, the bursting head device comprising: (a)a bursting head housing consisting essentially of (i) an integrated,substantially hollow cone body, and (ii) an end cap coupled to theposterior end of said cone body, said cone body dimensioned to burst apipe when pulled through said pipe; and (b) a clevis protruding from theposterior end of said end cap and attached to said end cap so as toswivel independent of said end cap, such that when said clevis iscoupled to a tang protruding from the anterior end of a replacement pipecarrier, said carrier can rotate and articulate about said burstinghead.
 10. The bursting head device of claim 9 wherein said cone bodyfurther comprises a cutting knife on its outer surface.
 11. The burstinghead device of claim 9 wherein said cone body further comprises an axialopening at its anterior end dimensioned to receive a cable.
 12. Thebursting head device of claim 11 wherein said cone body interior housesa cable gripping mechanism comprising: a plurality of interconnectingcable gripper jaws, the plurality of jaws together defining a conehaving an outer surface dimensioned to fit against the interior of saidbursting head cone body at its anterior end and having a threaded innersurface competent to grip a said cable, each said cable gripper jawmember comprising a magnet on each of its lateral interconnectingsurfaces, the magnet positioned to contact and repel the magnet on theadjacent jaw member.